U.S. Pat. No. 715,654 (Friend) teaches a gravity cell using of a porous partition placed between the upper layer of zinc sulfate electrolyte and the lower layer of copper sulfate electrolyte to prevent the two electrolytes from mixing together during periods of inactivity. “To these ends I divide the cell horizontally into two compartments, containing, respectively, the positive and negative elements of the battery, by a partition adapted to prevent the solid particles of matter from passing from one element to the other, but at the same time permitting the proper and necessary communication between the positive and negative compartments to sub serve the best results or produce the maximum efficiency. The separating partition or disk may consist of pasteboard or other suitable material possessing the absorbent or porous property or forming a filter against the passage of solid particles.”
However, said partition placed between the two half cells acts as a resistance force to the motion of the charge carriers thus increasing the internal cell resistance resulting in diminished output current. The preferred embodiments of the present invention do not utilize porous barriers.
However, the gravity cell disclosed in U.S. Pat. No. 715,654 (Friend) has the disadvantages of:                a. An eroding zinc anode that requires periodic replacement from the outside world;        b. The eroding zinc anode causing a buildup of excess zinc sulfate solution within the cell that requires removal to the outside world; and        c. Consumption of copper from the copper sulfate solution as copper is plated out onto the copper cathode, requiring the addition of more copper sulfate crystals from the outside world.        d. Buildup of plated copper onto the cathode requiring removal to the outside world.        e. Diminished output current per cross sectional area due to the use of a partition to keep the two electrolytic solutions separate. Said partition increases the internal cell resistance and therefore reduces the available electrical current per given cell.        f. The electric energy produced does not come from gravity but rather comes from the oxidation of the zinc anode.        
Energy from the outside world went into the zinc anode during the refining of zinc ore into zinc metal. The zinc anode stores this energy of refining as stored potential energy within the pure zinc anode. The stored potential energy is released back to the outside world as electric energy by way of oxidizing the zinc metal anode back into the zinc ore zinc sulfate. Gravity by way of buoyancy forces does the work of maintaining the stratification of the two electrolytes.                A galvanic cell in which the chemical energy converted into electrical energy is arising from the concentration difference of a single chemical species electrolyte at the two electrodes of the cell. An example is a divided cell consisting of two silver electrodes surrounded by silver nitrate electrolytes of different concentrations. Nature will tend to equalize the concentrations. Consequently, silver cations will be spontaneously reduced to silver metal at the electrode (cathode) in the higher concentration electrolyte, while the silver electrode (anode) in the lower concentration electrolyte will be oxidized to silver cations. Electrons will be flowing through the external circuit (from the anode or negative electrode to the cathode or positive electrode) producing a current, and nitrate anions will diffuse through the separator. This process will continue till the silver nitrate concentration is equalized in the two compartments of the cell. However, the voltage output of the cell decreases as the silver nitrate concentration gradient becomes equalized in the two compartments of the cell making the concentration cell unusable in situations that need a constant voltage output voltage source.        
U.S. Pat. No. 6,746,788 (Borsuk) states that, “Concentration cells utilizing external fields” teaches “The embodiments in both FIGS. 3A and 3B can be thermally reconditioned for repeated generation of electricity by exposing the cells to a cold temperature reservoir. This thermal processing reduces the solubility of the salt in electrolyte, causing the precipitation or reformation of solid 38, thus returning the cells to their original conditions.” “When the temperature of the cell is increased, the solubility of the salt is increased in the aqueous electrolyte. As solid 38 dissolves into electrolyte, sub volumes of electrolyte that are localized around the salt attain a temporarily higher solute concentration compared to regions or sub volumes of the electrolyte that are distant from the dissolving salt.”
A cold temperature applied to a saturated or near saturated electrolyte solution causes the solute to precipitate out of the solution and gravity causes the precipitating solute to collect in a low area of the solute/solvent container. When heat is applied to the electrolyte solution, the precipitated solute at the low area of the solute/solvent container re-dissolves into the electrolyte solution causing the re-dissolving solute to diffuse uniformly throughout the solvent, wherein “the free energy of the diffusion reaction may be used to generate electricity.”
For the Borsuk reference, energy is expended drawing out heat energy from the electrolyte solution to cause the solute to precipitate out of solution; and more energy is expended reheating the electrolyte to re-dissolve the precipitated solute back into solution to drive the diffusion reaction, wherein it is movement of heat energy rather than gravitational energy that is being converted to electricity. The Borsuk device uses more energy to drive the precipitation and dissolving process than it produces in electric energy.
The gravoltaic cell of the present invention is a transducer that converts gravitational force, by way of buoyancy forces, into electromotive force strong enough to push electrons through an external electric load resistance.
For galvanic cells, it is desirable to have both 1) the largest possible electrochemical junction disparity between the anode of a first chemical species and the compartmentalized homogeneous stationary volume of dissociated aqueous reactant cations of the second chemical species in immediate contact with the surface of the anode of the first chemical species and 2) the highest possible number of reactant cations of the second chemical species in immediate contact with the surface of the anode of the first chemical species. Meeting both these conditions provides the large electrochemical junction disparity needing to produce useful anode-reactant cation reactions that produce useful electromotive force, while at the same time provides a sufficiently high number of reactant cations to react with the anode to produce useful electrical current.
A concentration cell is a limited form of a galvanic cell that has two equivalent half-cells (or compartments) of the same aqueous reactant chemical species differing only in concentrations, but not in chemical species, in contact with two electrodes of the same chemical species as the reactant chemical species. A concentration cell is a limited source of electrical energy because it fails to provide any chemical species disparity at the junction between the anode and the reactant cation volume in contact with the anode.
A concentration cell is a limited source of electrical energy because it fails to provide a high concentration of reactant cation chemical species in contact with the anode, relative to the concentration of reactant cation chemical species in contact with the cathode.
A concentration cell requires a concentration difference of 10 times or greater of the single reactant chemical species to produce 30 millivolts (with luck) at room temperature, this is an unlikely event in a single container limited to gravitational and or magnetic forces.
In order to provide a good electrochemical junction disparity between the anode of one chemical species and the similar reactant cation volume of the same chemical species, the concentration of reactant cations must be very small, that is, a large concentration of one chemical species within the anode and a small concentration of the same chemical species within reactant volume, which in turn severely limits the number of chemical reactions occurring between the anode and the reactant volume at the interface between the anode and the reactant volume, and limits the total electrical current available to an external electrical load. On the other hand, in order to provide a good concentration of reactant cation chemical species in contact with the anode, the concentration of reactant cations must be near saturation, which in turn severely limits the concentration disparity between the anode and the reactant cation volume, which in turn severely limits the junction potential or voltage available to an external electrical load. The concentration disparity has the inherent problem of having two limitations working at cross purposes.
A concentration cell produces a small voltage as it attempts to reach concentration equilibrium of the aqueous reactant. This equilibrium occurs when the concentration of a single reactant in both cells are equal. Because an order of magnitude concentration difference of the single reactant produces less than 30 millivolts at room temperature, concentration cells are not typically used for energy storage. Specifically, a concentration cell is a limited form of a galvanic cell because it utilizes an electrochemically passive similar anode/cation concentration junction disparity between an anode of the first chemical species and a reactant cation volume of the first chemical species.
U.S. Pat. No. 8,288,995 (Jimbo, et al.) states that “As has been described above, since the amount of electrolyte in a valve-regulated lead-acid battery is lower than that in a fluid-type lead-acid battery, it is difficult to alleviate differences in sulfuric acid concentration between the bottom and top of the battery (difficult to diffuse SO.sub.4.sup.2−). In particular, as shown in FIG. 7, in the case of a valve-regulated lead-acid battery in which the positive electrode and negative electrode height is 100 mm or more, it becomes particularly difficult to alleviate the difference in sulfuric acid concentration between the bottom and top of the battery, thereby resulting in prominent stratification and lowering charge acceptance particular in low-temperature environments. In addition, high-rate charging using large current values becomes difficult.” However, the '995 patent teaches that it is difficult to alleviate the difference in sulfuric acid concentration between the bottom and top of the battery by diffusion.
U.S. Pat. No. 4,565,748 (Dahl) states that; “Large lead-acid batteries suffer from the problem of electrolyte sulfation and stratification. When a cell is charged, acid is formed at the plates and this more dense acid tends to sink to the bottom of the cell. In tall cells, where diffusion is insufficient to overcome the density gradient, it is necessary to provide some mechanical agitation in order to circulate the electrolyte and maintain a homogeneous electrolyte. However, the '748 patent teaches that in tall cells diffusion is insufficient to overcome the density gradient.
Practical and convenient cells are needed for producing robust and long-lived electrochemical cells for generating electrical power and delivering said electrical power to an external workload. Several approaches have been proposed, but none have found commercial acceptance.
What is needed is a gravoltaic cell that provides an electrochemically active chemical species disparity between the anode of a first chemical species and a reactant cation volume of a second chemical species. What is needed is a gravoltaic cell that utilizes positive and negative buoyancy to sustain electrochemically active chemical species disparity between an anode of the first chemical species and the reactant cation volume of the second chemical species. What is needed is a gravoltaic cell that plates out the eroded and dissolved anode chemical species onto the cathode, wherein the anode and the cathode may be interchanged thus eliminating the need to add new anode material to the system from the outside world, where neither the cell body nor the cation volumes are inverted.
What is needed is a gravoltaic cell that plates out excess dissolved anode chemical species onto the cathode at the same rate as anode material is being dissolved into solution at the anode, resulting in a fixed amount of anode cations within the cell, thereby eliminating the need to remove material from or add material to the outside world. What is needed is a gravoltaic cell that maintains a fixed amount of cations within the cell, thereby eliminating the need to remove material from or add material to the outside world. What is needed is a gravoltaic cell that has the ability to interchange the two electrodes as mass is transferred from the anode to the cathode, thereby eliminating the need to remove material from or add material to the outside world.